1. Field of The Invention
The present invention relates to a lightning protecting system for a wind power generation installation.
2. Conventional Art
Conventionally, at a rotor casing which incorporates a wind power generator a lightning conductor is provided, and at the same time, in order to protect the wind power generator and a control unit thereof (herein below called inclusively as a wind power generation device) from a lightning hit on a wind mill vane made of a low resistance conductor, a lightning protection device is constituted while providing a spark ring on the wind mill vane and an opposing conductor thereto with a discharge gap.
Great many wind power generation installations are these days being built to obtain a clean energy and are also being planned. Since wind mills are generally built at high on a flat site with no obstacles, the wind mills likely suffer lightnings, therefore, it is necessary to take sufficient counter measures to such lightnings.
It is observed that with regard to lightnings in summer season, although the voltages of the lightnings are high, but the current value of the lightning impulse is not so high as well as the duration of the impulse current is comparatively short. Therefore, for the lightnings having such lightning impulse current, the installation can be sufficiently protected through spark discharges with the discharge gap.
However, with regard to lightnings in winter season, the current value of the lightning impulse is large and the duration time thereof is also long. Therefore, it was observed that if the lightning impulse current is large, an over voltage increases which likely damages the wind power generation device, in particular, electronic parts thereof.
In view of such problems, an object of the present invention is to provide a lightning protection system for a wind power generation installation which effectively protects a wind power generation device for lightnings having a large current value of lightning impulses as well as a large duration time.
Another object of the present invention is to provide a lightning arrester system for a multiplicity of wind mills disposed at one site which permits a cost reduction.
The present invention is characterized by providing a protection device with a lightning arrester constituted by a non-linear resistance body such as a zinc (ZnO) type lightning arrester, in place of a conventional protection device with a spark gap. A zinc oxide type lightning arrester exhibits such a voltage-current characteristic which shows a substantially constant electric field intensity (V/cm) with respect to a broad band of current density (A/cm2). Namely, the zinc oxide type lightning arrester shows a proper protective characteristic and discharge current withstanding property in a medium electric field region in which an over voltage is applied as well as in a high electric field region which is affected by the inherent resistance of zinc oxide crystallines concerned.
The present invention is characterized by selecting, in particular, a non-linear resistance body having the above referred to characteristics and represented by a zinc oxide type element, and, specifically, provides the following devices.
The present invention provides a lightning protection system provided at a wind power generator in which wind mill vanes are rotated by wind force and electric power is generated by making use of the rotating force thereof, wherein at a rotor casing incorporating the wind power generator a non-linear resistance body is provided so as to face the wind mill vanes.
The present invention provides a lightning protection system provided at a wind power generator in which wind mill vanes are rotated by wind force and electric power is generated by making use of the rotating force thereof, wherein a conductor ring is provided on the wind mill vanes and at a rotor casing incorporating the wind power generator, a non-linear resistance body is provided so as to face the conductor ring with a gap.
The present invention provides a lightning protection system provided at a wind power generator in which wind mill vanes are rotated by wind force and electric power is generated by making use of the rotating force thereof, wherein at a rotor casing incorporating the wind power generator a zinc oxide type lightning arrester element is provided so as to face the wind mill vanes.
The present invention provides a lightning protection system provided at a wind power generator in which wind mill vanes are rotated by wind force and electric power is generated by making use of the rotating force thereof, wherein a conductor ring is provided on the wind mill vanes and at a rotor casing incorporating the wind power generator, a zinc oxide type lightning arrester element is provided so as to face the conductor ring with a gap.
The present invention provides a lightning protection system provided at a wind power generator in which wind mill vanes are rotated by wind force and electric power is generated by making use of the rotating force thereof, wherein, over a plurality of wind mills arranged in an array a lightning conductor is stretched and is earthed to the ground.